1. Field of the Invention
This invention is related to an improved gasket groove for use in a sealing member. More particularly, the invention relates to a sealing member having a groove to receive a gasket, preferably in the form of an O-ring.
2. Description of the Prior Art
A common expedient for sealing a surface of one member to another member is to provide a gasket so that a resilient seal is obtained. In many instances the gasket is placed in a groove so as to retain the gasket in position and a further common expedient is to use an O-ring as the gasket member. An O-ring is a continuous member which, in cross-section, in the non-deformed state, is circular. O-rings are a preferred gasket configuration because of their simplicity, economy, uniformity, dependability and availability.
The usual configuration of a groove for receiving an O-ring gasket is a parallel sided slot, usually of substantially rectangular cross-sectional configuration with the dimension of the groove being such that in the normal, non-sealing state, the O-ring gasket extends slightly beyond the sealing surfaces. When the member is moved to a closed position the O-ring is compressed, thereby providing a resilient seal. The parallel sided O-ring groove is successful in applications where the gasket is not inclined to be dislodged. For more demanding application, others have provided a groove having a lip adjacent the sealing surface to help retain the O-ring in position.
One particular use of an O-ring gasket is in butterfly type valves. In this type valve a disc has a circumferential sealing surface which, when the valve is in closed position, contacts a similar circumferential sealing surface inside the valve body. One problem with the use of O-rings in high pressure environments is that fluid pressure builds within the groove beneath the O-ring. Sudden changes of fluid pressure can cause the O-ring to be expelled from the groove. In order to attempt to solve this problem, small diameter pressure relief openings have been drilled from the sidewall of the valve disc into the lower portion of the O-ring groove in order to relieve pressure. While this helps alleviate the possibility of expulsion of the O-ring from the groove, it is not a complete solution to the problem since sudden pressure changes may not be relieved quickly enough to prevent the O-ring being displaced.
An object of the present invention is to provide an improved configuration for a groove to receive a gasket, particularly an O-ring type gasket, wherein the gasket is retained within the groove to a higher degree of certainty than with existing O-ring groove configurations.
This general object as well as other and more specific objects of the invention will be fulfilled in the following description and claims, taken in conjunction with the attached drawings.